Studies of monolayer cultures of dispersed pituitary cells have shown that ergocryptine and other dopaminergic drugs inhibit prolactin synthesis and decrease prolactin mRNA levels. It was also found that dopaminergic drugs stimulate the degradation of newly synthesized prolactin. Future work will investigate whether the dopaminergic regulation of prolactin mRNA levels involves changes in the transcription of the prolactin gene or in the stability of prolactin mRNA. These studies will utilize pulse and pulse-chase labeling of cultured pituitary cells. Studies of prolactin gene transcription will also utilize isolated pituitary cell nuclei.